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Additional Development Guidance

Replacement dwellings in the Countryside

We published a new Chief Planning Officer's Advice Note on Barn Conversions and Replacement dwellings in the Countryside in February 2023. It replaced the previous guidance note on replacement dwellings in the countryside.

You can find all our Chief Planning Officer Notes on our Planning Policy Guidance webpage.

Permitted development rights in respect of agricultural buildings

Converting agricultural buildings to dwellings - Class Q development

New Class Q legislation came into force on 21 May 2024. The Town and Country Planning (General Permitted Development etc.) (England) (Amendment) Order 2024 ( Any applications on or after this date, will be subject to the new rules.  

If your application was submitted before 21st May, please refer to old legislation. The Town and Country Planning (General Permitted Development) (England) Order 2015 (

These Permitted Development rights:

  • have been created to support sustainability

These permit agricultural buildings to be converted to up to ten dwelling houses.  The amount of space you can convert has increased to 1,000 m². However the maximum size of any dwelling is now 150 m². Therefore in order to have ten new dwellings under Class Q, each one will need to be 100 m² each. (An increase from the previous 5 units and 865 square metres).

Note, that until the end of 20th May 2025, you may apply for any development which would have been compliant with the old legislation.  You will not however benefit from the extensions under the new legislation. (see below)

You can now extend to the rear of the barn or agricultural building by up to 4m on any hard surface which was present on or before 24th July 2023 or if it didn’t exist on that date has existed for at least 10 years.

A range of conditions and criteria need to be met. These are set out in the Regulations. 

The changes will support the agricultural sector and rural communities by providing;

  • further flexibility for farmers to undertake works on their agricultural units, 
  • enable development of former agricultural buildings,
  • farm diversification and
  • deliver new homes without having to submit a planning application.

The Government wishes to help rural development. But it is not without limitations. These are to limit the impact of such development on the countryside. Safeguarding clauses include:

  • landscape designations
  • tenant farms
  • safe development and occupation of such dwellings.

Our  Class Q Prior Notification Guidance Note is being updated to reflect the changes. The website will be updated shortly.

Erection or extension of agricultural building for agricultural purposes

You can find this information on our Planning guidance for businesses webpage.  Please view the 'Other guidance for businesses' section and select the 'Farming' option.

Annexe Guidance Note

Residential annexes are a common form of development. They can allow relatives to live with their family with a degree of independence. Annexes are considered to be acceptable by the Council in many cases.  Please note:

  • applications for residential annexes can vary a great deal
  • you need to support these applications with sufficient evidence.

This ensures that applications do not result in proposals which are effectively the same as creating a new dwelling.  Officers use the Annexe Guidance Note (January 2024) to assess proposals. Please note:

  • the guidance does not have the weight of "adopted policy"
  • it provides consistency in our approach
  • it aims to help agents and applicants do the same.

Use Class factsheet

You can find more information on the changes to use classes using this link: Use Class factsheet.

Guidance on access and facilities for Fire Service

Cornwall Council Building Control, Planning and the Fire & Rescue Service have produced guidance on water supplies for firefighting and access for fire appliances.

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